Vulnerable people in the UK have been warned not to eat runny eggs due to a developing salmonella outbreak.

The Food Standards Agency (FSA) has said that under fives, over 65s, pregnant women and people with health conditions should avoid under-cooked or runny eggs when eating out.

Freshly-made products that may contain uncooked eggs such as mayonnaise, souffle and hollandaise sauce should also be avoided, the agency said.

One person has died and 200 have fallen ill during the UK-wide salmonella outbreak, according to the UK Health Security Agency (UKHSA) ranging in age from under one to 90 years old.

This has been linked to people eating imported eggs, the agency says, as it investigates the outbreak.

FSA chief scientific adviser Ian Young said: “If people are eating out or consuming eggs or egg-containing products from cafes and restaurants then for those people in particular who are young, elderly, pregnant or vulnerable, it's important to make sure that any eggs or egg products that you consume in those settings have been very well cooked.”

The expert added that it is fine for people to buy British eggs from supermarkets, as the chickens that produce them are vaccinated against common strains of salmonella.

“There is no link to those eggs to this current outbreak,” he told the BBC, describing it as “unusually large and rapidly increasing”.

“People need to be careful,” he added.